body, html {
    margin: 0;
    padding: 0;
}
body{
    background-size:cover;
    background-attachment:fixed
}
.main{
    width: 100%;
    height: 100%;
    background: url(../images/bg.jpg) no-repeat center;
    -webkit-background-size: cover;
    min-height: 100vh;
    display: flex;
    text-align: center;
}
.main .all{
    width: 80%;
    height: 80%;
    margin: 50px auto;
    display: flex;
    align-items: center;
    flex-direction: column;
}
.main .chat{
    width: 23%;
    height: 80%;
    margin: 0 5em 0 -9em;
    display: flex;
    align-items: center;
    flex-direction: column;
}
#prompt{
    width: 450px;
    height: 50px;
    margin-top: 1em;
    align-items: center;
    background-color: white;
    line-height: 50px;
    border-radius: 0.3em;
}
.textarea {
    border: none;
    outline: none;
    width: 100%;
    height: 70px;
    border-radius: 0.4em;
    padding: 0.5em 0.5em;
    font-size: 17px;
    font-family: '微软雅黑';
    resize: none;
}
.messages{
    height: 360px;
    width: 100%;
    border-radius: 0.4em;
    margin-bottom: 0.5em;
    background-color: white;
    padding: 1.5em 0.5em;
    overflow: auto;
}
button.submit{
    margin-top: 0.5em;
    width: 108%;
    padding: 0.7em 0.5em;
    border-radius: 0.3em;
    outline: none;
    border: none;
    font-size: 17px;
}
button.submit:active{
    background-color: #97ab4f;
    transform: translateY(2px);
}
div.me{
    display: flex;
    align-items: flex-end;
    flex-direction: column;
    margin: 0.4em;
}
div.me .message{
    background-color: #47d486;
    max-width: 80%;
    border-radius: 0.5em;
    padding: 0.3em 0.3em;
    text-align: start;
}
div.you{
    display: flex;
    align-items: flex-start;
    flex-direction: column;
    margin: 0.4em;
}
div.you .message{
    background-color: #fa976d;
    max-width: 80%;
    border-radius: 0.5em;
    padding: 0.3em 0.3em;
    text-align: start;
}
.back{
    width: 400px;
    padding: 1em 0.2em;
    color: red;
    font-size: 18px;
    outline: none;
    border: none;
    border-radius: 0.3em;
    margin-top: 0.2em;
}
.timer{
    /*border: 5px solid whitesmoke;*/
    font-size: 35px;
    border-radius: 50%;
    color: white;
    margin-bottom: 0.2em;
    width: 42px;
    height: 42px;
}